Assistance Please with Door Up-Down-Stop Circuit

Discussion in 'General Electronics Chat' started by ElectroMan283, Nov 19, 2015.

  1. ElectroMan283

    Thread Starter New Member

    Nov 19, 2015
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    DOOR UP-DOWN-STOP CONTROL CIRCUIT

    This is my door up/down control circuit. The DPDT switch acts as an upper and lower limit switch, which is great, except the door must go all the way to the top (or bottom) before DPDT activates and allows direction change via the Control Box. I need the ability to stop door, at any point, and reverse directions (up to down, or down to up).
    I am assuming this would be done with relays, but… Can anyone help me accomplish this?
    Thank you,
    upload_2015-11-19_10-6-22.png upload_2015-11-19_10-6-22.png
     
  2. dl324

    Distinguished Member

    Mar 30, 2015
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    Study how a garage door opener works and decide which bits you want to implement.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You could also use separate N.C. L.S.'s for Up/Dwn and use a DPDT with centre off switch for UP/DWN should give better control.
    Max.
     
  4. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Thats what the emergency stop button is for on your drawing.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    But once his DPDT limit flips over, he has only has one choice.
    Max.
     
  6. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Not if he uses n.c. limit switches, instead of the dpst.
     
  7. dl324

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    He wants the ability to stop at any point and/or (unclear) reverse directions. That's going to take more than switches or relays.
     
  8. MaxHeadRoom

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    That is what I pointed out in my 1st post. ;) Just using the E-stop doesn't do it.
    Max.
     
  9. MaxHeadRoom

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    See Post #3.
    Max.
     
  10. dl324

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    OK, I'll bite. See post #1. The door has to close all the way before it can reverse.
     
  11. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    I assume the door has a mechanical limit switch that flicks one switch in the centre, so if he removes this and puts two normally closed limit switches, top and bottom of the door, this should solve the problem.
     
  12. ElectroMan283

    Thread Starter New Member

    Nov 19, 2015
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    Would a momentary SPDT with center off do it, as in the attached pic?

    upload_2015-11-19_11-26-22.png
     
  13. MaxHeadRoom

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    Yes that is the circuit I indicated but the switch needs to be maintained.
    Otherwise you would need a latching contact across each to maintain the respective circuit.
    You can get this switch in a toggle or a maintained on-off-on operator panel control switch.
    Max.
     
  14. ElectroMan283

    Thread Starter New Member

    Nov 19, 2015
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    I am looking at a DPDT switch, bit do not see how it would work, unless perhaps it was a DPDT rocker type switch. Is that what you are thinking?
     
  15. MaxHeadRoom

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    That should read SPDT centre off.
    Max.
     
  16. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    Not sure what your box does and why ground goes to -24 V.

    Anyway, it's extremely easy to do and it will give you instantaneous stops.

    bear with me, without a diagram.

    Take two SPDT relays and wire them such that the common terminals go to the motor. Wire the NC (Normally closed terminals) to ground.
    So, with everything off, the motor sees ground on both sides or the motor is shorted. Shorting the motor is essentially dynamic braking.

    Your switch, the SPDT center off can be (ON) - OFF - (ON) or ON - OFF - ON where the () indicate momentary.

    SO, pick one and what ever logic, so that one coil is energized in alternating positions.

    OK, no limit switches yet.

    When it's at a limit, you want to cut the coil power to the coil of the relay that is causing it to move in the direction it's moving.
    So the same thing similarly for the other limit switch.

    Both limits being activated is a non-possibility and it then would not be possible to move the motor.

    You MIGHT want to add a service switch that shorts out both limit switches. Definitely overload protect the motor in case the switches should fail. The limit switches don't carry the full motor current.

    One drawback is that jogging too fast or flipping the switch back and forth could say pop a fuse quickly. Not sure how to do it, but not allowing the motor to start for a short time after stopping would help that. A thermal fuse would likely work fine. One car window quit working one day just because it was hot outside. the thermal had too cool down.
     
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